'\" t
.\"     Title: zmq_msg_copy
.\"    Author: [see the "AUTHORS" section]
.\" Generator: DocBook XSL Stylesheets v1.78.1 <http://docbook.sf.net/>
.\"      Date: 12/13/2017
.\"    Manual: 0MQ Manual
.\"    Source: 0MQ 4.2.3
.\"  Language: English
.\"
.TH "ZMQ_MSG_COPY" "3" "12/13/2017" "0MQ 4\&.2\&.3" "0MQ Manual"
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.SH "NAME"
zmq_msg_copy \- copy content of a message to another message
.SH "SYNOPSIS"
.sp
\fBint zmq_msg_copy (zmq_msg_t \fR\fB\fI*dest\fR\fR\fB, zmq_msg_t \fR\fB\fI*src\fR\fR\fB);\fR
.SH "DESCRIPTION"
.sp
The \fIzmq_msg_copy()\fR function shall copy the message object referenced by \fIsrc\fR to the message object referenced by \fIdest\fR\&. The original content of \fIdest\fR, if any, shall be released\&. You must initialise \fIdest\fR before copying to it\&.
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The implementation may choose not to physically copy the message content, rather to share the underlying buffer between \fIsrc\fR and \fIdest\fR\&. Avoid modifying message content after a message has been copied with \fIzmq_msg_copy()\fR, doing so can result in undefined behaviour\&. If what you need is an actual hard copy, allocate a new message using \fIzmq_msg_init_size()\fR and copy the message content using \fImemcpy()\fR\&.
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.RE
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Never access \fIzmq_msg_t\fR members directly, instead always use the \fIzmq_msg\fR family of functions\&.
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.RE
.SH "RETURN VALUE"
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The \fIzmq_msg_copy()\fR function shall return zero if successful\&. Otherwise it shall return \-1 and set \fIerrno\fR to one of the values defined below\&.
.SH "ERRORS"
.PP
\fBEFAULT\fR
.RS 4
Invalid message\&.
.RE
.SH "EXAMPLE"
.PP
\fBCopying a message\fR. 
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.if n \{\
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.nf
zmq_msg_t msg;
zmq_msg_init_size (&msg, 255);
memcpy (zmq_msg_data (&msg, "Hello, World", 12);
zmq_msg_t copy;
zmq_msg_init (&copy);
zmq_msg_copy (&copy, &msg);
\&.\&.\&.
zmq_msg_close (&copy);
zmq_msg_close (&msg);
.fi
.if n \{\
.RE
.\}
.sp
.SH "SEE ALSO"
.sp
\fBzmq_msg_move\fR(3) \fBzmq_msg_init\fR(3) \fBzmq_msg_init_size\fR(3) \fBzmq_msg_init_data\fR(3) \fBzmq_msg_close\fR(3) \fBzmq\fR(7)
.SH "AUTHORS"
.sp
This page was written by the 0MQ community\&. To make a change please read the 0MQ Contribution Policy at \m[blue]\fBhttp://www\&.zeromq\&.org/docs:contributing\fR\m[]\&.
